Clinical evaluation of biological fluids, such as blood, has long been an important procedure in the examination and treatment of individuals seeking medical attention. For example, it is conventional, in medical practice, to withdraw a blood sample from a patient into a collection tube. Thereafter, the blood sample is subjected to laboratory procedures (e.g., centrifugal separation of the blood sample into plasma or serum and cells) and analysis.
In recent years the tubes provided for collecting blood have been glass tubes which are evacuated or vacuumized by the manufacturer and used in conjunction with a device having a double-ended needle cannula. Typically, such a collection tube comprises an impervious glass tube having one end permanently closed (e.g., by an integral, semi-spherical portion of the glass tube) and the other end closed by a rubber stopper or diaphragm which is adapted to be punctured and penetrated by one end of a double-ended needle cannula. In use, one end of the double-ended needle cannula is inserted into the patient's vein and the stoppered end of the tube is thrust onto the other end of the needle cannula so as to pierce the stopper or diaphragm. Since the tube is evacuated or vacuumized, blood from the patient is thereby sucked into the collection tube.
Examples of evacuated or vacuumized glass collection tubes of the type described above are shown in U.S. Pat. Nos. 2,460,641 and 3,771,965.
Processing of the blood in glass collection tubes by laboratory personnel has been found, in some instances, to give rise to the transfer of disease (e.g., hepatitis) or infection to personnel handling such tubes. Disease transference or infection may occur if the glass tube breaks and the blood contacts the hands or other body parts of the handling personnel. In addition, contamination to the personnel may occur in the transferring of collected blood or other biological fluids to another container or to processing apparatus due to the aerosol action of the blood being processed.
Another disadvantage associated with the use of glass collection tubes is that they are relatively expensive.
The problems associated with the cost of glass tubes and the transference of disease due to breakage of blood-filled tubes could be eliminated by employing a nonbreakable tube, such as plastic, for example, In the past, however, plastic tubes were thought to be unacceptable because they could not maintain a vacuum over an extended period of time, i.e., from the time of evacuation or vacuumization by the manufacturer until the tube is actually employed to collect a fluid sample. It is recognized that plastic is not as impervious to air as glass, and during the storage time between evacuation by the manufacturer and use, air can migrate through the plastic and the connection between the plastic tube and the rubber stopper thereto to destroy or partially destroy any vacuum in the tube.
The problems of contamination of laboratory personnel and possible disease transference arising from processing of blood samples after collection are addressed in U.S. Pat. No. 3,782,197. That patent proposes a blood collection tube provided with a resilient piston member in the bottom of the tube for forcing collected blood into another container for subsequent analysis. However, the collection tube of the U.s. Pat. No. 3,782,197 is designed to be evacuated or vacuumized by the manufacturer, and thus does not solve the breakage problems and other problems and costs associated with glass collection tubes.